1. Field of the Invention
The present invention relates generally to the field of photon sensing. More particularly, the present invention relates to an optomechanical photon detector and a multicolor sensor that can incorporate this detector. Specifically, a preferred implementation of the present invention relates to a multicolor infrared sensor that is based on a stack of frequency specific optomechanical photon detectors, each of which operates based on measurement of photoinduced lattice strain. The present invention thus relates to infrared sensors of the type that can be termed multicolor.
2. Discussion of the Related Art
Detecting photons, especially infrared photons, is a challenging endeavor. There are two types of infrared radiation detectors currently used: photon detectors and thermal detectors.
Infrared photon detectors are usually based on semiconductor materials. Their operation is based on the conversion of photon energy to charge carriers. As is well known, these charge carriers include electrons and/or holes. These charge carriers can be detected as current or voltage. Some photon detectors can attain detectivities of approximately 10.sup.13 cm Hz.sup.1/2 /W but require the device to be cooled in order to minimize the dark current that interferes with the signal to be measured. However, this cooling requirement increases the complexity and cost of such devices.
Infrared thermal detectors are based on the conversion of photon energy to heat which results in temperature induced changes in the detector. The temperature of the detector is measured. This requires the device to have high thermal isolation. In addition, to maximize their sensitivity, their response times are unacceptably slow, on the order of a few milliseconds. Heretofore, these two factors have represented major obstacles to the wider implementation of thermal detectors as infrared imagers. The theoretical detectivity of thermal detectors is on the order of approximately 10.sup.10 cm Hz.sup.1/2 /W at room temperature. A value for detectivity of approximately 10.sup.9 cm Hz.sup.1/2 /W has already been demonstrated in this temperature regime.
What is needed, therefore, is an improved approach to infrared sensing that has high detectivity, but does not require cooling. What is also needed is an improved approach to infrared imaging that provides both a multicolor capability and a rapid response time. Heretofore, these requirements have not been met.
Within this application several publications are referenced by superscripts composed of Arabic numerals within parentheses. Full citations for these, and other, publications may be found at the end of the specification immediately preceding the claims. The disclosures of all these publications in their entireties are hereby expressly incorporated by reference into the present application for the purposes of indicating the background of the present invention and illustrating the state of the art.